Re: Some info given by 'mdadm --detail --export' are not convenient to use

[Francis Moreau <francis.moro@gmail.com>]

On 04/12/2014 01:43 AM, NeilBrown wrote:
> On Fri, 11 Apr 2014 13:01:49 +0200 Francis Moreau <francis.moro@gmail.com>
> wrote:
> 
>> Hello,
>>
>> I'm writing a tool that relies udev lib in order to manage block
>> devices connected to my computer.
>>
>> One thing that I need is to retrieve disks contained by a RAID array.
>>
>> The current usefull information exported by udev are, for example:
>>
>> MD_DEVICES=3
>> MD_DEVICE_loop0p1_DEV=/dev/loop0p1
>> MD_DEVICE_loop0p1_ROLE=0
>> MD_DEVICE_loop1p1_DEV=/dev/loop1p1
>> MD_DEVICE_loop1p1_ROLE=1
>> MD_DEVICE_loop2p1_DEV=/dev/loop2p1
>> MD_DEVICE_loop2p1_ROLE=2
>>
>> but this is not really easy to exploit since I need to know the disk
>> names in order to poke the devices used by the array :-/
>>
>> why not simply using ?
>>
>> MD_DEVICE_DEV_1=/dev/loop0p1
>> MD_DEVICE_ROLE_1=0
>>
> 
> What number would I use for spare devices?
> Certainly something like this could be done, but it wasn't.
> 
> Maybe what you are really asking is:
> 
> "Could we please have another record which lists all the devices, e.g.
>   MD_DEVICE_LIST=loop0p1 loop1p1 loop2p1
> ??"
> 

Yes please, that's what I was asking for: there's currently no easy way
to retrieve the list of disks that is part of an array. Currently we have:

MD_DEVICE_loop0p1_DEV=/dev/loop0p1

The name of the property involves the value of the property.

> Obviously you can extract that from the output above, but it might be easier
> to have it explicitly.

Yes I can but it's not very convenient.

> 
> Would that meet your need, or have I misunderstood you completely?
> 

Yes, it would.

Thanks.